Recognized in Owl Canyon, Larimer County, Colorado. Is primarily a red shale; has some gray sandy limestone and some gypsum locally. Thickness ranges from 43 to 56 feet. Overlies Minnekahta limestone; underlies Forelle limestone, both of Phosphoria group [intent to designate as a group not stated]. Age is Permian. Report includes measured sections.
Named for exposures in Spring Creek Valley, 1 mi south and 2 mi west of Glendo (type locality), Platte Co., WY, in Denver basin.

Source: Modified from GNU records (USGS DDS-6; Denver GNULEX).

Reduced in stratigraphic rank and assigned as one of eight members to the Goose Egg Formation in Albany and Carbon Cos, WY in the Greater Green River basin. Ranges from 50 to 80 ft thick. Is widespread throughout most of eastern WY. Where the usually underlying Minnekahta Limestone Member or the Opeche Shale Member (both newly assigned to the Goose Egg) are missing, Glendo rests on Owl Canyon Formation. Overlain by Forelle Limestone Member, newly assigned to the Goose Egg. Intertongues with Franson Member of Park City Formation in central WY. Correlates with Whitehorse Sandstone and equivalents in CO, NE, and KS, and with Harriman Shale, Falcon Limestone, and Bergen Shale Members of Lykins Formation of CO. Consists dominantly of red-orange mudstone and siltstone abundantly mottled by yellowish- to greenish-gray spots as much as three-fourths inch in diameter. Bedded contorted by slumping and flowage. Early Permian age. Correlation chart; cross section.

Source: GNU records (USGS DDS-6; Denver GNULEX).